1. Technical Field
Building with a roof having a wind deflection system.
2. Background Information
The vast number of buildings now built in highly exposed regions and the apparently increasing frequency of category 4 and 5 hurricanes all portend more widespread destruction of houses and other buildings. Much of the destruction is needless. The loss of roofs in particular, with collateral damage to life and property, may be preventable.
Many houses and other small buildings in the Caribbean and the U.S. “Hurricane Belt” can lose their roofs to category 3 and 4 storms. Weaknesses are common in the tie-down of roof structure to the walls below, and are also found in the inadequacy of the roof framing itself to withstand hurricane uplift forces without breaking.
Several regions now require resistance to category 5 storms for new construction, and a method of fastening roof structure to exterior wall structure by means of steel straps may be completed during construction. However, there are millions of houses and other low-rise buildings completed without such fastenings or other adequate reinforcement, and the job of “retrofitting” such buildings with steel strap or such devices intended for new construction tends to be disruptive and expensive, even perilous, because trim, soffits, claddings and sheathings may first have to be removed, technicians often working by ladder from the exterior of the building, to access and secure the structural components, after which the whole must be “made good”. Several other such retrofit measures are essentially cable or strap arrangements or nets that usually must be skillfully applied to or over the roof each time a storm is anticipated and removed and safely stored after it's over. There is a need for providing a more efficient and less expensive method for protecting buildings, particularly existing buildings and more particularly their roofs, against hurricane force winds.
In aerodynamics there generally are two types of flow around an object: laminar and turbulent. Laminar flow is generally believed to have less drag, but it may also be prone to a phenomenon called “separation.” Once the separation of a laminar boundary layer occurs, drag rises dramatically because of eddies that form in the gap. Turbulent flow has more drag initially, but also has better adhesion, and therefore is less prone to “separation.” Therefore, if the shape of an object is such that separation occurs easily, it is believed to be better to turbulate the boundary layer in order to increase adhesion and reduce eddies (which may mean a significant reduction in drag). For example, dimples on golf balls turbulate the boundary layer thereabout, as do vortex generators on airplane wings.